Co-overexpression of the HMGR and FPS genes enhances artemisinin content in Artemisia annua L.

Abstract

Artemisinin, a sesquiterpene lactone endoperoxide derived from the plant Artemisia annuaL., is considered to be the most effective antimalarial drug. To increase the production of artemisinin, the hmgr and fps genes which encode two key enzymes involved in artemisinin synthesis, were cloned from A. annua, respectively. The genes were inserted between the cauliflower mosaic virus 35S promoter and nopaline synthase terminator to construct the expression cassettes, and were then cloned into the plant expression vector pCAMBIA2300 to obtain the p2300-gfh vector containing both the hmgr and fps genes. An Agrobacterium-mediated method was used to stably transform A. annua, and 38 independent transgenic plants were obtained. Polymerase chain reaction and Southern blot analysis confirmed that the foreign genes were successfully introduced into the A. annua genome. The results obtained by high-performance liquid chromatography-evaporative light scattering detection showed that the artemisinin contents of most transgenic plants were higher than those in control plants. The highest artemisinin content in transgenic plants was about 1.8-fold that of the control plants. The results of real-time fluorescence quantitative analysis showed that the expression of hmgr and fps was enhanced in the transgenic plants analyzed. This study demonstrates that overexpression of the hmgr and fps genes are an effective approach to increase artemisinin content in A. annua L. Key words: Artemisia annua L. (Asteraceae), artemisinin, genetic engineering, hmgr andfps genes.